Overall, the main goal is the detailed understanding of the squalene yields lanosterol conversion. We are now studying (1) the effect of squalene oxide structural modifications on the course of enzymic cyclization in order to understand better the bioorganic mechanism of lanosterol biosynthesis, (2) the question of new intermediates in sterol biosynthesis, and (3) certain non-enzymic cyclizations which shed light on the chemistry of the enzymic process.